Service Manual
Microwave Oven
Model : KOR-634R0S
KOR-638R0S
DAEWOO ELECTRONICS CO., LTD.
http://svc.dwe.co.kr
36
PRECAUTIONS TO BE OBSERVED BEFORE AND
DURING SERVICING TO AVOID POSSIBLE
EXPOSURE TO EXCESSIVE MICROWAVE ENERGY
(a) Do not operate or allow the oven to be operated with the door open.
(b) Make the following safety checks on all ovens to be serviced before activating the magnetron or other microwave source, and make repairs as necessary: (1) Interlock operation, (2) Proper door closing, (3) Seal and
sealing surfaces (arcing, wear, and other damage), (4) Damage to or loosening of hinges and latches, (5)
Evidence of dropping or abuse.
(c) Before turning on power to the microwave oven for any service test or inspection within the microwave generating compartments, check the magnetron, wave guide or transmission line, and cavity for proper alignment, integrity, and connections.
(d) Any defective or misadjusted components in the interlock, monitor, door seal, and microwave generation
and transmission systems shall be repaired, replaced, or adjusted by procedures described in this manual
before the oven is released to the owner.
(e) A microwave leakage check to verify compliance with the Federal performance standard should be performed on each oven prior to release to the owner.
TABLE OF CONTENTS
SAFETY AND PRECAUTIONS ...........................................................................................................................................2
1. FOR SAFE OPERATION............................................................................................................................................2
2. FOR SAFE SERVICE PROCEDURES......................................................................................................................2
SPECIFICATIONS ...............................................................................................................................................................3
EXTERNAL VIEW................................................................................................................................................................4
1. OUTER DIMENSION..................................................................................................................................................4
2. FEATURE DIAGRAM .................................................................................................................................................5
3. CONTROL PANEL .....................................................................................................................................................6
INSTALLATION ...................................................................................................................................................................8
OPERATIONS AND FUNCTIONS.......................................................................................................................................9
DISASSEMBLY AND ASSEMBLY....................................................................................................................................10
INTERLOCK MECHANISM AND ADJUSTMENT.............................................................................................................19
TROUBLE SHOOTING GUIDE .........................................................................................................................................20
MEASUREMENT AND TEST ............................................................................................................................................24
1. MEASUREMENT OF THE MICROWAVE POWER OUTPUT..................................................................................24
2. MICROWAVE RADIATION TEST ............................................................................................................................25
3. COMPONENT TEST PROCEDURE ........................................................................................................................26
WIRING DIAGRAM............................................................................................................................................................27
PRINTED CIRCUIT BOARD..............................................................................................................................................28
1. CIRCUIT CHECK PROCEDURE..............................................................................................................................28
2. PCB CIRCUIT DIAGRAM .........................................................................................................................................31
3. P.C.B. LOCATION NO..............................................................................................................................................32
EXPLODED VIEW AND PARTS LIST...............................................................................................................................33
1. DOOR ASSEMBLY...................................................................................................................................................33
2. CONTROL PANEL ASSEMBLY ...............................................................................................................................33
3. TOTAL ASSEMBLY..................................................................................................................................................33
1
SAFETY AND PRECAUTIONS
1. FOR SAFE OPERATION
Damage that allows the microwave energy (that cooks or heats the food) to escape will result in poor cooking and may
cause serious bodily injury to the operator.
IF ANY OF THE FOLLOWING CONDITIONS EXIST, OPERATOR MUST NOT USE THE APPLIANCE.
(Only a trained service personnel should make repairs.)
(1) A broken door hinge.
(2) A broken door viewing screen.
(3) A broken front panel, oven cavity.
(4) A loosened door lock.
(5) A broken door lock.
The door gasket plate and oven cavity surface should be kept clean.
No grease, soil or spatter should be allowed to build up on these surfaces or inside the oven.
DO NOT ATTEMPT TO OPERATE THIS APPLIANCE WITH THE DOOR OPEN.
The microwave oven has concealed switches to make sure the power is turned off when the door is opened.
Do not attempt to defeat them.
DO NOT ATTEMPT TO SERVICE THIS APPLIANCE UNTIL YOU HAVE READ THIS SERVICE MANUAL.
2. FOR SAFE SERVICE PROCEDURES
1. If the oven is operative prior to servicing, a microwave emission check should be performed prior to servicing the
oven.
2. If any certified oven unit is found to servicing, a microwave emission check should be performed prior to servicing the
oven.
(a) inform the manufacturer, importer or assembler,
(b) repair the unit at no cost to the owner,
(c) attempt to ascertain the cause of the excessive leakage,
(d) tell the owner of the unit not to use the unit until the oven has been brought into compliance.
3. If the oven operates with the door open, the service person should tell the user not to operate the oven and contact
the manufacturer and CDRH immediately.
IMPORTANT
The wire in this mains lead coloured in accordance with the following code.
Green-and-yellow : Earth
Blue
: Neutral
Brown
: Live
As the colours of the wires in the manins lead of this appliance may not correspond with the coloured markings
identifying the terminals in your plug, proceed as follows.
The wire which is coloured green-and-yellow must be connected to the terminal in the plug which is marked with
the letter E , earth symbol or coloured green-and-yellow.
The wire which is coloured blue must be connected to the terminal which is marked with the letter N or coloured
black.
The wire which is coloured brown must be connected to the terminal which is marked with the letter L or
coloured red.
NOTE :
The oven is designed for counter-top use only.
2
SPECIFICATIONS
MODEL
KOR-634R0S, KOR-638R0S
POWER SUPPLY
POWER CONSUMPTION
230V~50Hz, SINGLE PHASE WITH EARTHING
MICROWAVE
1,200 W
MICROWAVE ENERGY OUTPUT
800W
MICROWAVE FREQUENCY
2450MHz
OUTSIDE DIMENSIONS (W X H X D)
465 x 279 x 360 mm (18.3 x 11.0 x 14.2 in)
CAVITY DIMENSIONS (W X H X D)
290 x 220 x 306 mm (11.4 x 8.7 x 12.0 in.)
NET WEIGHT
Approx. 13 kg (28.7 Ibs.)
TIMER
59 min.
FUNCTION SELECTIONS
MICROWAVE
POWER SELECTIONS
5 LEVELS
CAVITY VOLUME
0.7 Cu. Ft.
* SPECIFICATIONS ARE SUBJECT TO CHANGE WITHOUT NOTICE.
3
EXTERNAL VIEW
1. OUTER DIMENSION
4
2. FEATURE DIAGRAM
5. OVEN LAMP
Automatically turns on during oven operating.
1. DOOR SEAL
Door seal maintains the microwave within the oven
cavity and prevents microwave leakage.
6. SAFETY INTERLOCK SYSTEM
2. DOOR HOOK
When the door is closed, it will automatically lock shut.
If door is opened while oven is operating, magnetron
tube will immediately stop operating.
7. CONTROL PANEL
8. GLASS COOKING TRAY
Made of special heat resistant glass. The tray must
always be in proper position before operating. Do not
cook food directly on the tray.
3. DOOR SCREEN
Allows viewing of food. Microwave cannot pass
through perforations in screen.
9. OVEN FRONT PLATE
10. ROLLER GUIDE
Supports the glass cooling tray.
4. SPATTER SHIELD
Protects the microwave outlet from splashes of cooking foods.
5
3. CONTROL PANEL
KOR-634R
1. Display — Cooking time, power level, indicators and
present time are displayed.
6. Dial knob — Used to set time and weight.
7. Stop/Clear — Used to stop the oven operation or to
erase all entries.
2. Power — Used to set power level.
3. Defrost — Used to defrost by weight or time.
8. Start/Easy cook — Used to start the oven operation
and also increase the reheat time by 30 seconds.
4. Clock — Used to set clock.
5. Auto cook — Used to using a program or to reheat.
6
KOR-638R
KOR-638K
Stop/
Clear
7
Auto Cook
Defrost
1. Dinner Plate
2. Soup
3. Beverage
4. Fresh Vegetable
3
Power
2
1
Clock
M/W Def.
Lock
4
g
Auto Cook
5
6
8
Start
Easy Cook
1. Display — Cooking time, power level, indicators and
present time are displayed.
6. Dial knob — Used to set time and weight.
7. Stop/Clear — Used to stop the oven operation or to
erase all entries.
2. Power — Used to set power level.
3. Defrost — Used to defrost by weight or time.
8. Start/Easy cook — Used to start the oven operation
and also increase the reheat time by 30 seconds.
4. Clock — Used to set clock.
5. Auto cook — Used to using a program or to reheat.
7
INSTALLATION
1. Steady, flat location
This microwave oven should be set on a steady, flat surface.
This microwave oven is designed for counter top use only.
2. Leave space behind and side
All air vents should be kept a clearance. If all vents are covered during operation, the oven may overheat and, eventually,
cause oven failure.
3. Away from Radio and TV sets
Poor television reception and radio interference may result if the oven is located close to a TV, Radio, antenna or feeder
and so on.
4. Away from heating appliances and water taps
Keep the oven away from hot air, steam or splash when choosing a place to position it, or the insulation might be
adversely affected and breakdowns occur.
5. Power supply
➢ Check your local power source.
This microwave oven requires a current of approximately 6 amperes, 230Volts, 50Hz grounded outlet.
➢ Power supply cord is about 0.8 meters long.
➢ The voltage used must be the same as specified on this oven. Using a higher voltage may result in a fire or other accident causing oven damage. Using low voltage will cause slow cooking, We are not responsible for damage resulting from
use of this oven with a voltage of ampere fuse other than those specified.
➢ This appliance is supplied with cable of special type, which, if samaged, must be repaired with cable of same type.
Such a cable can be purchased from DAEWOO and must be installed by a Qualified Person.
6. Examine the oven after unpacking for any damage such as:
A misaligned door, broken door or a dent in cavity.
If any of the above are visible, DO NOT INSTALL, and notify dealer immediately.
7. Do not operate the oven if it is colder than room temperature
(This may occur during delivery in cold weather.) Allow oven to become room temperature before operating.
EARTHING INSTRUCTIONS
This appliance must be earthed. In the event of an electrical short circuit, earthing reduces the risk of the electric shock
by providing an escape wire for the electric current. This appliance is equipped with a cord having a earthing wire with a
earthing plug. The plug must be plugged into an outlet that is properly installed ant earthed.
WARNING
Improper use of the earthing plug can result in a risk of electric shock. Consult a qualified electrician or serviceman if
the earthing instructions are not completely understood, or if doubt exists as to whether the appliance is properly
earthed, and either:If it is necessary to use an extension cord, use only a 3-wire extension cord that has a 3-blade
earthing plug, and a 3-slot receptacle that will accpt the plug on the appliance. The marked rating of the extension
cord should be equal to or greater than the electrical rating of the appliance, or Do not use an extension cord.
8
OPERATIONS AND FUNCTIONS
1. Connect the main lead to an electrical outlet.
2. After placing the food in a suitable container, open the oven door and put it on the glass tray. The glass tray must always
be in place during cooking.
3. Close the door securely.
4. When the oven door is opened, the light turns off.
5. The oven door can be opened at any time during operation by touching the door release button on the control panel.
The oven will automatically shut off. To restart the oven, close the door and then touch START.
6. Each time a pad is touched, a BEEP will sound to acknowledge the touch.
7. The oven automatically cook on full power unless set to a lower power level.
8. The display will show : 0 when the oven is plugged in.
9. Time clock returns to the present time when the cooking time ends.
10. When the STOP/CLEAR pad is touched during the oven operatiion, the oven stops cooking and all information retained.
To erase all information (except the present time), touch the STOP/CLEAR pad once more. If the oven door is opened
during the oven operation, all information is retained.
11. If the START pad is touched and the oven does not operate, check the area between the door and door is closed
securely. The oven will not start cooking under the door is completely closed or the program has been reset.
Make sure the oven is properly installed and plugged into the electrical outlet.
Wattage output chart
The power level is set by pressing the POWER pad. The chart shows the display, the power level and the percentage of
power.
Touch POWER button
Power level (Display)
Approximate Percentage of Power
Once
P-HI
100%
3 times
P-80
80%
5 times
P-60
60%
7 times
P-40
40%
9 times
P-20
20%
9
DISASSEMBLY AND ASSEMBLY
Cautions to be observed when trouble shooting.
Unlike many other appliances, the microwave oven is high-voltage, high-current equipment.
It is completely safety during normal operation.
However, carelessness in servicing the oven can result in an electric shock or possible danger from a short circuit.
You are asked to observe the following precautions carefully.
1. Always remove the power plug from the outlet before servicing.
2. Use an insulated screwdriver and ware rubber gloves when servicing the high voltage side.
3. Discharge the high voltage capacitor before touching any oven components or wiring.
(1) Check the grounding.
Do not operate on a 2-wire extension cord.
The microwave oven is designed to be used with grounded.
It is imperative, therefore, to make sure it is grounded
properly before beginning repair work.
(2) Warning about the electric charge in the high voltage capacitor.
For about 30 seconds after the operation stopped and electric
charge remains in the high voltage capacitor.
When replacing or checking parts, short between oven chassis and
the negative high terminal of the high voltage capacitor, by using a
properly insulated screwdriver to discharge.
4. When the 12A fuse is blown out due to the operation of the monitor
switch; replace primary interlock switch, secondary interlock switch and
interlock monitor switch.
5. After repair or replacement of parts, make sure that the screws are
properly tightened, and all electrical connections are tightened.
6. Do not operate without cabinet.
CAUTION : Service personnel should remove their watches whenever working close to or replacing the magnetron.
CAUTION : When servicing the appliance, need a care of touching or replacing high potential parts because of
electrical shock or exposing microwave. These parts are as follows - HV Transformer, Magnetron,
HV Capacitor, HV Diode, HV fuse.
10
1. To remove cabinet
1) Remove three screws on cabinet back.
2) Push the cabinet backward.
2. To remove door assembly
1) Remove two screws which secure the stopper hinge
top.
2) Remove the door assembly from top plate of cavity.
3) Reverse the above for reassembly.
NOTE : After replacing the door assembly, perform a check of correct alignment with the hinge and cavity front plate.
11
3. To remove door parts.
KOR-634R
DOOR ASSEMBLY
KOR-634R0S:3511712140
REF NO.
PART CODE
PART NAME
DESCRIPTION
A01
3512203850
FRAME DOOR
ABS XR-401, H-2938
1
A02
3517005620
BARRIER-SCREEN*O
TEMP GLASS T3.2
1
A03
3515204100
STOPPER HINGE*T AS
KOR-63150S
1
A04
3511706120
DOOR PAINTING AS
KOR-634R0S
1
A05
3517002800
BARRIER-SCREEN*I
PE 0.1T
1
A06
3512300200
GASKET DOOR
PP
1
A07
3513100730
HOOK
POM BLACK
1
A08
3515101310
SPRING HOOK
HSW-3
1
A09
7001503311
SCREW MACHINE
PAN 5X33 MFZN
2
A10
3512603210
HANDLE DOOR
STEEL NI + CR
1
A11
3511601500
DECORATOR LOGO
AL T1.5
1
A12
3511604610
DECORATOR DOOR*U
STS T0.6
1
A13
3511604600
DECORATOR DOOR*T
STS T0.6
1
A14
3516003940
SPECIAL DOUBLE TAPE
SI-161 T0.15 27MM
1
12
Q TY
REMARK
KOR-638R
A01
A02
A03
A04
A05
A06
A07
A08
A09
A10
DIG
ITA
L
A12
A11
A13
DOOR ASSEMBLY
KOR-638R0S:3511714970
DESCRIPTION
Q’ty
REF. NO
PART CODE
PART NAME
A01
3517005680
BARRIER-SCREEN*O
PMMA T1.5
1
A02
3511603810
DECORATOR DOOR
ABS SG-175 SG-0760D
1
A03
3512205260
FRAME DOOR
ABS SG-175 SG-0760D
1
A04
3515204110
STOPPER HINGE*T AS
KOR-636T1S
1
A05
3511706120
DOOR PAINTING AS
KOR-634R0S
1
A06
3517002800
BARRIER-SCREEN *I
PE T0.1
1
A07
3512300210
GASKET DOOR
PP
1
A08
7122401211
SCREW TAPPING
T2S TRS 4*12 MFZN
2
A09
3513100730
HOOK
POM BLACK
1
A10
3515101320
SPRING HOOK
HSW-3
1
A11
3511601500
DECORATOR LOGO
AL T1.5
1
A12
3511607300
DECORATOR HANDLE
ABS SG-175 SG-0760D
2
A13
3512604110
HANDLE DOOR
MP-0160
1
13
REMARK
(1) Remove the gasket door from door weld as.
(2) Remove the barrier screen inner from weld as.
(3) Remove the door frame from door weld as.
(4) Remove the stopper hinge top from door weld as.
(5) Remove the spring and the hook.
(6) Remove the barrier screen outer from door frame.
(7) Reverse the above steps for reassembly.
4. Method to reduce the gap between the door seal and the oven front surface.
(1) To reduce gap located on part A
¥ Loosen two screws on stopper hinge top,
and then push the door to contact the door
seal to oven front surface.
¥ Tighten two screws.
(2) To reduce gap located on part B
¥ Loosen two screws on stopper hinge under,
and then push the door to contact the door
seal to oven front surface.
¥ Tighten two screws.
NOTE : A small gap may be acceptable if the microwave leakage does not exceed 4mW/cm2.
14
5. To remove control panel parts.
KOR-634R
CONTROL PANEL ASSEMBLY
KOR-634R0S: PKCPSWZYOO
REF NO.
PART CODE
PART NAME
DESCRIPTION
Q TY
B01
3513404620
KNOB VOLUME
ABS XR-401, H-2938
1
B02
3511604510
DECORATOR C-PANEL
STS T0.6
1
B03
3516003910
SPECIAL DOUBLE TAPE
SI-161 T0.15
1
B04
3515501530
WINDOW DISPLAY
PMMA T2.0
1
B05
3516721460
CONTROL PANEL
ABS XR-401, H-2938
1
B06
3516907430
BUTTON FUNCTION
ABS XR-401, COATING
1
B07
PKBPMSZY00
SUB PCB AS
KOR-634R0S
1
B08
7121401611
SCREW TAPPING
T2S PAN 4X16 MFZN
3
B09
PKMPMSZY00
MAIN PCB AS
KOR-634R0S
1
B10
7621301011
SCREW TAPPING
T2S TRS 4X12 MFZN
8
B11
3516906320
BUTTON FUNCTION
ABS XR-401, COATING
2
REMARK
1) Remove the screw which secure the control panel, push up two snap fits and draw forward the control panel assembly.
2) Remove screws which secure the PCB assembly to control panel.
3) Disconnect membrane tail from the connector of the PCB assembly.
4) Detach the function buttons and knob from the control panel.
5) Reverse the above steps for reassembly.
15
KOR-638R
B07
B08
B09
B06
B11
B10
B05 B06
B03
B01
B07
B04
CONTROL PANEL ASSEMBLY
KOR-638R0S: PKCPSWETIO
B02
REF NO.
PART CODE
PART NAME
DESCRIPTION
Q TY
B01
3513405280
KNOB VOLUME
ABS SG-175, SG-0760D
1
B02
3515501570
WINDOW DISPLAY
KOR-638K
1
B03
3511604580
DECORATOR C-PANEL
ABS SG-175, SG-0760D
1
B04
3516726220
CONTROL PANEL
ABS SG-175, SG-0760D
1
B05
3516909800
3511607500
ABS SG-175, SG-0760D
PC
1
B06
BUTTON FUNCTION-B
DECORATOR BUTTON
2
2
B07
3516907590
BUTTON FUNCTION-A
ABS SG-175, SG-0760D
B08
PCB BUTTON AS
SCREW TAPPING
KOR-638K
1
B09
PKBPMSET00
7621301011
T2 PAN 3X10 PW MFZN
5
B10
PKMPMSET00
PCB MAIN AS
KOR-638K
1
B11
7122401211
SCREW TAPPING
T2S TRS 4X12 MFZN
4
16
REMARK
6. To remove high voltage capacitor.
1) Remove a screw which secure the grounding ring
terminal of the H.V. diode and the capacitor holder.
2) Remove the H.V. diode from the capacitor holder.
3) Reverse the above steps for reassembly.
◆ High voltage circuit wiring
7. To remove magnetron.
1) Remove a screw which secure the magnetron.
2) Remove the magnetron.
3) Reverse the above steps for reassembly.
NOTE : Never install the magnetron without the metallic gasket plate which is packed with each magnetron to prevent microwave leakage. Whenever repair work is carried out on magnetron, check the microwave leakage. It shall
not exceed 4mW/cm2 for a fully assembled oven with door normally closed.
17
8. To remove wind guide assembly.
1) Remove a screw which secure the wind guide assembly.
2) Draw forward the wind guide assembly.
3) Pull the fan from the motor shaft.
4) Remove two screws which secure the motor shaded pole.
5) Remove the motor shaded pole.
6) Reverse the above steps for reassembly.
9. To remove H.V.transformer.
1) Remove four screws holding the H.V.transformer.
2) Remove the H.V.transformer.
3) Reverse the above steps for reassembly.
18
INTERLOCK MECHANISM AND ADJUSTMENT
The door lock mechanism is a device which has been specially designed to completely eliminate microwave radiation when
the door is opened during operation, and thus to perfectly prevent the danger resulting from the leakage of microwave.
(1) Primary interlock switch
When the door is closed, the hook locks the oven door. If the door is not closed properly, the oven will not operate.
When the door is closed, the hook pushes the button of the microswitch. Then the button of the primary interlock switch
bring it under ON condition.
(2) Secondary interlock switch and interlock monitor switch
When the door is closed, the hook pushes the lock lever downward. The lock lever presses the button of the interlock
monitor switch to bring it under NO condition and presses the button of the secondary interlock switch to bring it under
ON condition.
ADJUSTMENT :
Interlock monitor switch
When the door is closed, the interlock monitor switch should be changed (NO condition) before other switches are closed.
When the door is opened, the interlock monitor switch should be changed (NC condition) after other switches are opened.
(3) Adjustment steps
a) Loosen the two mounting screws.
b) Adjust interlock switch assembly position.
c) Make sure that lock lever moves smoothly after adjustment is completed.
d) Tighten completely two mounting screws.
NOTE :
Microwave emission test should be performed after adjusting interlock mechanism. If the microwave smission exceed
4mW/cm2, readjust interlock mechanism.
19
TROUBLE SHOOTING GUIDE
Following the procedure below to check if the oven is defective or not.
1. Check grounding before trouble checking.
2. Be careful of the high voltage circuit.
3. Discharge the high voltage capacitor.
4. When checking the continuity of the switches, fuse or high voltage transformer, disconnect one lead wire from these parts
and check continuity with the AC plug removed. To do otherwise may result in a false reading or damage to your meter.
NOTE : When electric parts are checked, be sure the power cord is not inserted the wall outlet.
Check wire harness, wiring and connected of the terminals and power cord before check the parts listed
below.
(TROUBLE 1) Oven does not operate at all ; any inputs can not be accepted.
Condition
Fuse blows
Check
Result
Check continuity of interlock monitor switch
with door closed
(COM
NC)
Continuity
Cause
Remedy
Malfunction of
interlock
monitor switch
Replace
Shorted contacts
of primary interlock
switch
Replace
Shorted contacts of
primary interlock
switch.
Replace
Defective low voltage transformer
Replace
Defective high
voltage transformer
Replace
Note 1.
No
Continuity
No
Continuity
Check continuity of primary interlock switch contact with door partially
open until interlock monitor switch contact close
Note 1.
Continuity
Continuity
Check continuity of primary interlock switch contact with door partially
open until interlock monitor switch contact close
(COM
NO)
0  or
infinite
Check continuity of
primary winding of low
voltage transformer
Note 1.
Approx.
150~310
(normal)
Disconnect high voltage
fuse and operate the unit
Fuse again
blows
20
Condition
Outlet has
proper voltage.
Fuse does not
blow.
Check
Result
Cause
Remedy
Check continuity of
magnetron
No
Continuity
Defective magnetron
Check continuity of
noise filter board
No
Continuity
Defective line filter
board
Replace
Check continuity of
power supply cord
No
Continuity
Open power supply
cord
Replace
Normal
Defective touch control circuit
Replace
Replace
NOTE : All these switches must be replaced at the same time, please refer to Interlock Mechanism and Adjustment.
(TROUBLE 2) Display shows all figures selected, but oven does not start cooking, even though desired program
and time are set and start pad is tapped.
Condition
Turn table
motor, and
oven lamp do
not turn on
Check
Result
Cause
Check continuity of
primary interlock
switch
No
Continuity
Malfunction of primary
interlock switch
Adjust or
Replace
Check continuity of
secondary interlock
and D.O.M. switchs
No
Continuity
Malfunction of secondary interlock and
D.O.M switch
Adjust or
Replace
Check D.C. voltage
being supplied to
RELAY (RY2) coil
0V
Defective touch control circuit
Approx
15 VDC
21
Faulty contacts of
RELAY (RY2) or open
relay coil
Remedy
Replace
Replace
(TROUBLE 3)
No microwave oscillation even though fan motor rotates.
Condition
Check
Result
No
microwave
oscillation
Check continuity
of high voltage
capacitor
terminals with
wires removed
Continuity
Defective high
voltage
transformer
Replace
Check continuity of
high voltage rectifier in forward and
backward direction
with DC megger
Continuity in
backward
direction
Defective high
voltage rectifier
Replace
Connect megger
leads to
magnetron
terminal and
magnetron body
Continuity
Defective
magnetron
Replace
Check resistance
of primary and
secondary coil of
high voltage
transformer
0 or
Defective high
voltage
transformer
Replace
Check continuity
of magnetron
with wires
removed
No
Continuity
Defective
magnetron
Replace
Check continuity
of filament
terminal of high
voltage
transformer
No
Continuity
Defective high
voltage
transformer
Replace
Check D.C.
voltage being
supplied to
RELAY (RY1)
coil
0V
Defective touch
control circuit
Replace
Approx
15 VDC
Faulty contacts of
RELAY (RY1) or
open relay coil
Replace
22
Cause
Remedy
(TROUBLE 4)
The following visual conditions indicate a probable defective touch control circuit or membrane
switch assembly.
1. Incomplete segments
(1) Segments missing
(2) Partical segments missing
(3) Digit flickering other than normal display slight flickering
(4) :0 does not display when power is on.
2. A distinct change in the display are not on when they numbers is the
display.
3. One or more digits in the display are not on when they should be.
4. Display indicates a number different from one touched.
5. Specific numbers (for example 2 or 3) will not display when the panel
is touched.
6. Display does not count down or up with time cooking or clock operation.
7. Oven is programable and cooks normally but no display shows.
8. Display obviously jumps in time while counting down.
9. Display counts down noticeably too fast while cooking.
10. Display does not show the time of day when clear pad is touched.
11. Oven lamp and turntable motor do not stop although cooking is finished. Check if the RELAY 2 contacts close if they are
close, replace touch control circuit.
Condition
Display does
not show
programming
at all, even it
keyboard is
touched
Check
Check each pad
for continuity of the
membrane keyboard
for the following
keyboard check
procedure
Result
Cause
Remedy
Normal
Malfunction
of touch control
circuit of
control box
sub-assembly
Replace control box
sub-assembly
Abnormal
Malfunction of
the membrane
keyboard
Replace the membrane keyboard
NOTE : Before following the particular steps listed above in the trouble shooting guide for the membrane keyboard s, failure, please check for the continuity of each wire-harness between the membrane keyboard
and P.C.B. assembly.
23
MEASUREMENT AND TEST
1. MEASUREMENT OF THE MICROWAVE POWER OUTPUT
Microwave output power can be checked by indirectly measuring the temperature rise of a certain amount of water
exposed to the microwave as directed below.
PROCEDURE
1. Microwave power output measurement is made with the microwave oven
supplied at rated voltage and operated at its maximum microwave power
setting with a load of 1000–5cc of potable water.
2. The water is contained in a cylindrical borosilicate glass vessel having a
maximum material thickness of 3 mm and an outside diameter of approximately 190 mm.
3. The oven and the empty vessel are at ambient temperature prior to the
start of the test.
The initial temperature of the water is 10–2ßC (50–3.6ßF)
It is measured immediately before the water is added to the vessel.
After addition of the water to the vessel, the load is immediately placed on
the center of the shelf, which is in the lowest normal position.
4. Microwave power is switched on.
5. Heating time should be exactly A seconds. (Refer to table as following)
Heating time is measured while the microwave generator is operating at full power.
The filament heat-up time for magnetron is not included.
6. The initial and final temperature of water is selected so that the maximum difference between the ambient and final
water temperature is 5K.
7. The microwave power output P in watts is calculated from the following formula :
P=4187 X ▲T/t
¥ ▲T is difference between initial and ending temperature.
¥ t is the heating time.
The power measured should be B (Refer to SPECIFICATIONS)W–10.0%.
CAUTION :
1. Water load should be measured exactly to 1 liters.
2. Input power voltage should be exactly specified voltage(Refer to SPECIFICATIONS).
3. Ambient temperature should be 20–2ßC(68–3.6ßF)
Heating time for power output:
A(second)
70
64
60
56
52
49
47
44
42
40
38
B(W)
600
650
700
750
800
850
900
950
1000
1050
1100
24
2. MICROWAVE RADIATION TEST
CAUTION :
1. Make sure to check the microwave leakage before and after repair of adjustment.
2. Always start measuring of an unknown field to assure safety for operating personnel from microwave energy.
3. Do not place your hands into any suspected microwave radiation field unless the safe density level is known.
4. Care should be taken not to place the eyes in direct line with the source of microwave energy.
5. Slowly approach the unit under test until the radiometer reads an appreciable microwave leakage from the unit
under the test.
PROCEDURES
1. Prepare Microwave Energy Survey Meter, 600cc glass
beaker, and glass thermometer 100ßC(212ßF).
2. Pour 275cc–15cc of tap water initially at 20–5ßC(68–9ßF) in
the 600cc glass beaker with an inside diameter of approx.
95mm(3.5in.).
3. Place it at the center of the tray and set it in a cavity.
4. Close the door and operate the oven.
5. Measure the leakage by using Microwave Energy Survey
Meter with dual ranges, set to 2450MHz.
1) Measured radiation leakage must not exceed the value
prescribed below. Leakage for a fully assembled oven with
door normally closed must be less than 4mW/cm2.
2) When measuring the leakage, always use the 5cm(2in.)
space cone with probe. Hold the probe perpendicular to
the cabinet and door. Place the space cone of the probe
on the door, cabinet, door seem, door viewing screen, the
exhaust air vents and the suction air vents.
3) Measuring should be in a counter-clockwise direction at a
rate of 1 in./sec. If the leakage of the cabinet door seem is
unknown, move the probe more slowly.
4) When measuring near a corner of the door, keep the probe
perpendicular to the areas making sure the probe end at
the base of the cone does not get closer than 2 in. from
any metal. If it does not, erroneous reading may result.
25
3. COMPONENT TEST PROCEDURE
¥ High voltage is present at the high voltage terminal of the high voltage transformer during any cooking cycle.
¥ It is neither necessary nor advisable to attempt measurement of the high voltage.
¥ Before touching any oven components or wiring, always unplug the oven from its power source and discharge the
capacitor.
1. High voltage transformer
(1) Remove connections from the transformer terminals and check continuity.
(2) Normal readings should be as follows:
Secondary winding ...................Approx. 110 –10%
Filament winding....................................Approx. 0
Primary winding .....................................Approx. 1
2. High voltage capacitor
(1) Check continuity of capacitor with meter on the highest OHM scale.
(2) A normal capacitor will show continuity for a short time, and then indicate 10M once the capacitor is charged.
(3) A shorted capacitor will show continuous continuity.
(4) An open capacitor will show constant 10M .
(5) Resistance between each terminal and chassis should be infinite.
3. High voltage diode
(1) Isolate the diode from the circuit by disconnecting the leads.
(2) With the ohmmeter set on the highest resistance scale measure the resistance across the diode terminals.
Reverse the meter leads and again observe the resistance reading.
Meter with 6V, 9V or higher voltage batteries should be used to check the front-back resistance of the diode, otherwise an infinite resistance may be read in both directions.
A normal diode s resistance will be infinite in one direction and several hundred K in the other direction.
4. Magnetron
For complete magnetron diagnosis, refer to Measurement of the Microwave Power Output .
Continuity checks can only indicate and open filament or a shorted magnetron.
To diagnose for an open filament or a shorted magnetron.
(1) Isolate magnetron from the circuit by disconnecting the leads.
(2) A continuity check across magnetron filament terminals should indicate 0.1 or less.
(3) A continuity check between each filament terminal and magnetron case should read open.
5. Fuse
If the fuse in the primary and monitor switch circuit is blown when the door is opened, check the primary and monitor
switch before replacing the blown fuse.
In case the fuse is blown by an improper switch operation, replace the defective switch and fuse at the same time.
Replace just the fuse if the switches operate normally.
26
WIRING DIAGRAM
27
PRINTED CIRCUIT BOARD
1. CIRCUIT CHECK PROCEDURE
1. Low Voltage Transformer check
¥ The low voltage transformer is located on the P.C.B.
¥ Measuring condition: input voltage : 230V/Frequency : 50Hz
Terminal Voltage
4-7
LOAD
AC 25.8 V
NO LOAD
AC 28.4 V
NOTE :
1. Refer to Circuit Diagram (point 4).
2. Secondary side voltage of the low voltage transformer changes in proportion to fluctuation of power source voltage.
3. The allowable tolerance of the secondary voltage is within – 5% of nominal voltage.
2. Voltage check
¥ Key check point
NO
CHECK POINT
1
IC 1 PIN 2, 21, 30, 34
2
IC 1 PIN 35
REMARK
—5 VDC
0V
—5V
3
T:20ms(50Hz)
T
IC 1 PIN 31 OR 32
0V
—5V
T
T: 250 ns (4MHz)
¥ Check method
NO
MEASURE POINT
1
MP1
2
MP2
WAVE FORM
REMEDY
REMARK
DC -5V–0.25V
Replace VL1, EC1
NO LOAD
DC -12V–2.0V
Replace EC2, D6, D11, D12
NO LOAD
NOTE :
Each measure point must be measured with GND points.
28
Measure Point
29
3. When there is no microwave oscillation
1) When touching START pad, oven lamp does not turn on.
Fan motor do not rotate, but cook indicator in display comes on.
* Cause : RELAY 2 does not operate. → refer to Circuit Diagram (Point 3)
- Check method
POINT
A
B
RELAY 2 ON
-5VDC
GND
RELAY 2 OFF
GND
-12VDC
STATE
2) When touching START pad, oven lamp turns on.
Fan motor and turntable rotate and cook indicator in display comes on.
* Cause : RELAY 1 does not operate. → refer to Circuit Diagram (Point 2)
- Check method
POINT
A
B
RELAY 1 ON
-5VDC
GND
RELAY 1 OFF
GND
-12VDC
STATE
4. When the door is opened during operation, the count down timer does not stop.
→ refer to Circuit Diagram (Point 1)
-Check method
POINT
A
B
1) DOOR OPEN
OPEN
-5VDC
2) DOOR CLOSED
CLOSE
GND
STATE
CHECK NO
1
METHOD
REMEDY
Check the stage (ON, OFF) of the door open monitor switch by
resistance measurement.
5. When the digital clock does not operate properly.
→ refer to Circuit Diagram (Point 5)
POINT
1
WAVE FORM
0V
—5V
T:20ms(50Hz)
T
* If clock does not keep exact time, you must check resistor R15, 16, zener diode ZD1.
30
Replace door open monitor
switch.
2. PCB CIRCUIT DIAGRAM
31
3. P.C.B. LOCATION NO.
NAME
NAME
SYMBOL
SPECIFICATION
PART CODE Q’TY REMARK
1
PCB MAIN
M166
82 X 146.8
3514321140
1
2
BUZZER
BZ1
BM-20K
3515600100
1
3
C ARRAY
CA1
5P(4) 1000PF M 50V
CN4XB-102M
1
4
CAPACITOR CERA
C6
102 50V Z AXIAL
CCZB1H102K
1
5
CAPACITOR CERA
C1~5, C7
104 50V Z AXIAL
CCZF1H104Z
6
6
CAPACITOR ELEC
EC1
16V RSS 100MF
CEXF1C101V
1
7
CAPACITOR ELEC
EC2
25V RSS 1000MF
CEXF1E102V
1
8
CONNECTOR WAFER
CN1
YW396-02V
3519150520
1
9
CONNECTOR WAFER
CN2
HLEM15S-1
4CW215SBDO
1
10
CONNECTOR WAFER
CN3
YW396-05AV
3519150510
1
11
DIODE SWITCHING
D1~6, D8~10
1N4148
DZN4148---
9
12
DIODE RECTIFY
D11,12
KN4004A
DZN4004A--
2
13
DIODE ZENER
ZD1
MTZ- 5.1VB 1/2W
DZTZ5R1B--
1
14
DIODE ZENER
ZD2
MTZ- 3.9VB 1/2W
DZTZ3R9B--
1
15
IC MICOM
IC1
TMP47C440BN-NGO4
13GS631R00
1
16
IC REGULATOR
VL1
MC7905C
1MC7905C--
1
17
LED DISPLAY
DP1
DDG-631H
DDDG631H--
1
18
R ARRAY
RA1
RGLD4X104J
RA-85X104J
1
19
R CARBON FILM
R19
1/4W
27
5%
RD-4Z270J-
1
20
R CARBON FILM
R13
1/6W 100
5%
RD-AZ101J-
1
21
R CARBON FILM
R1~R7
1/6W 330
5%
RD-AZ331J-
7
22
R CARBON FILM
R8,9,11,14,20
1/6W
1K
5%
RD-AZ102J-
5
23
R CARBON FILM
R15,16,17
1/6W 10K
5%
RD-AZ103J-
3
24
R CARBON FILM
R12
1/6W 100K
5%
RD-AZ104J-
1
25
R CARBON FILM
R18
1/6W
5%
RD-AZ105J-
1
26
RESONATOR CERA
CR1
KBR-4.0MKSTF
5PKBR40MKS
1
27
SW RELAY
RY1
G5G-1A 1C 1P DC12V
5SC0101121
1
28
SW RELAY
RY2
OJ-SS-112LM DC 12V
5SC0101404
1
29
TRANSISTOR
Q1~5, Q8~10
KRA-106M
TZRA106M--
8
30
TRANSISTOR
Q6
KTA-1270Y
TZTA1270Y-
1
31
TRANS POWER
LVT1
DMR-631FS
5EPV035303
1
32
WIRE COPPER
J1~J5,J8,J10~13,J15,J17
1/0.52 TIN COATING
85801052GY
12
7.5mm
33
WIRE COPPER
J9,J14,J16
1/0.52 TIN COATING
85801052GY
3
10.0mm
34
WIRE COPPER
J6,J7
1/0.52 TIN COATING
85801052GY
2
12.5mm
35
WIRE FLAT
WF1
15/90 WH C
WSJ-159007
1
1
PCB SUB
M167
82 X 161
3514321220
1
2
CONNECTOR WAFER
CN101
HLEM15R-1
4CW215RBDO
1
3
R CARBON FILM
R101, R102
1/6W 1K 5%
RD-AZ102J-
2
4
SW ROTARY
SW101
SDB161PVB17F123636
5S10109002
1
5
SW TACT
SW102~SW107
KPT-1115AM
5S50101Z93
6
6
WIRE COPPER
J101
1/0.52 TIN COATING
85801052GY
1
32
1M
MAIN PCB
SUB PCB
7.5mm
EXPLODED VIEW AND PARTS LIST
1. DOOR ASSEMBLY
Refer to Disassembly and assembly.
2. CONTROL PANEL ASSEMBLY
Refer to Disassembly and assembly.
3. TOTAL ASSEMBLY
33
NAME
A00
B00
F01
F02
F03
F04
F05
F06
F08
F09
F10
F11
F12
F13
F14
F15
F16
F17
F18
F19
F20
F21
F22
F23
F24
F25
F26
F27
F28
F29
F30
F31
F32
F33
F34
F35
F36
F37
F38
F39
F40
F41
F42
F43
F44
F45
F46
F47
F48
PART CODE
3510801310
7112401011
3516109000
3516109600
7112401011
7122401211
7122401211
35113AEQ0D
4413A90012
7112401011
7122401211
4415D67620
4415D67120
3518606200
7121403011
3963513100
3963512310
3512517000
3511800300
3518002200
3516004000
7272400811
3513003200
3518302200
3518400400
3518701100
3518113700
3516003700
3510311700
7112401011
3512100900
7272400811
3515201101
4415A17352
4415A66910
4415A17352
3513702610
3513811710
4415A17352
3513601600
7121400611
3966310100
3966310110
3518905300
3513003400
3516003700
3511406200
3517400620
3514700710
3512517300
3517203600
PART NAME
DOOR AS
CONTROL PANEL AS
CABINET
SCREW TAPPING
CAVITY WELD AS
CAVITY JOINT AS
SCREW TAPPING
SCREW TAPPING
SCREW TAPPING
CORD POWER AS
CLAMP POWER CORD
SCREW TAPPING
SCREW TAPPING
FUSE
FUSE
NOISE -FILTER
SCREW TAPPING
MOTOR SHADED POLE
MOTOR SHADED POLE
GUIDE WIND
FAN
MAGNETRON
SPECIAL SCREW
TAPTITE SCREW
HOLDER HV CARACITOR
CAPACITOR HV
DIODE HV
FUSE HV
TRANS HV
SPECIAL SCREW
BASE
SCREW TAPPING
FOOT
SECRW TAPTITE
STOPPER HINGE *U
SW MICRO
SW MICRO
SW MICRO
LEVER LOCK
LOCK
SW MICRO
LAMP
SCREW TAPPING
MOTOR SYNCRO
MOTOR SYNCRO
THERMOSTAT
HOLDER THERMOSTAT
SPECIAL SCREW
COVER WAVE GUIDE
COUPLER
ROLLER
GUIDE ROLLER
TRAY
34
DESCRIPTION
Refer to disassembly and assembly
Refer to disassembly and assembly
PCM T0.36 GE
T1 TRS 4*10 MFZN
CAVITY WELD AS
CAVITY JOINT AS
T1 TRS 4*10 MFZN
T2S TRS 4*12 MFZN
T2S TRS 4*12 MFZN
3X0.75 70X70 100-RTML
NYLON66
T1 TRS 4*10 MFZN
T2S TRS 4*12 MFZN
250V 12A 65TS
250V 12A MDA
DWLF-M12
T2S PAN 4X30 MFZN
120V 17W OEM-10DWC2-A07
230V 20W MW10CA-M02
PP
PP+30%GLASS
2M218H(MF)I
T2 BOLT FLANGE 5X12 DACRO
TT2 TRS 4*8 MFZN
SECC T0.6
2100VAC 0.98uF #187
HVR-1X-3AB 12KV #187
5KV 0.55A HV-41A55-02
DY-N80S0-63T
TT3 HEX 4X8 FLG MFZN
SBHG T0.8
T1 TRS 4*10 MFZN
PP DASF-130
TT3 TRS 4X8 MFZN
SCP-1 T2.5
VP-533A-OF SPNO #187 200G
VP-531A-OF/SZM-V16-FA-61
VP-533A-OF SPNO #187 200G
POM
POM
VP-533A-OF SPNO #187 200G
BL 240V 25W T25 C7A H187
T2S PAN 4X6 MFZN
220V 2.5W GM-16-24FD12
220V 2.5W M2LJ49ZT52
OFF:75 ON:65 H #187 NB
PBT
TT3 HEX 4X8 FLG MFZN
HEATPROOF PP
XAREC
TEFLON
PP 5116MF6 A353B
GLASS
Q’TY
1
1
1
3
1
1
1
1
1
1
1
1
1
1
1
1
2
1
1
1
1
1
1
1
1
1
1
1
1
4
1
5
2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
3
1
1
DAEWOO ELECTRONICS CO., LTD.
686, AHYEON-DONG MAPO-GU SEOUL, KOREA
C.P.O. BOX 8003 SEOUL, KOREA
TELEX: DWELEC K28177-8
CABLE: DAEWOOELEC
S/M NO. : R634R0S002
PRINTED DATE: DEC, 2001